The present invention relates to a lensed fiber array using lensed fibers each consisting of an optical fiber whose front end face is formed in a lens shape and a production method therefor, and more particularly to a lensed fiber array prevented from deterioration in optical characteristics by any adhesive sticking to the front end faces of its lensed fibers and a production method therefor.
In recent years, lensed fibers have come into use as optical fibers for coupling to laser diodes (LD) and semiconductor optical amplifiers (SOA). Lensed fibers are optical fibers whose front end faces are formed in a lens shape; they can converge lights having come incident by the lens effect of the fiber themselves and take those lights into the fiber cores without fail. Therefore, they have the advantage of being able to enhance the coupling efficiency of LDs and SOAs. And along with the increasing arrayed (multi-core) use of LD and SOAs, the demand is also rising for lensed fiber arrays in each of which lensed fibers are aligned in a multi-core manner.
Incidentally, an ordinary optical fiber array is configured of a plurality of optical fibers, a substrate in one of whose faces a plurality of grooves respectively matching the plurality of optical fibers are formed, and a fixing member which aligns and fixes the plurality of optical fibers by pressing them against the grooved face of the substrate, and these elements are fastened to one another with an adhesive.
Therefore, an ordinary optical fiber array can be produced by preparing a substrate in one of whose faces a plurality of grooves respectively matching the plurality of optical fibers are formed, mounting the plurality of optical fibers over the plurality of grooves in that substrate, aligning and fixing the plurality of optical fibers by pressing them against the grooved face of the substrate with a fixing member, and fastening these elements to one another with an adhesive.
The optical fiber array produced in this manner undergoes a process known as facing, namely polishing of its front end faces, to polish the front end faces of the optical fibers or to remove any adhesive that may have become stuck to the front end faces of the optical fibers, because if any adhesive is stuck to the front end faces of the optical fibers (especially the front end faces of the fiber cores), the optical characteristics of the optical fibers may be significantly deteriorated.
As a lensed fiber array has a basically similar structure to the ordinary optical fiber array, it can be produced in a manner similar to the above-described production method.
However, if a lensed fiber array is subjected to end face polishing after it is produced according to the above-described production method, there arises a problem that the lens parts at the front ends of the lensed fibers will be chipped off and become unable to function as originally intended, even though any adhesive that may have become stuck to the front end faces of the optical fibers can be removed. Thus, it is difficult to remove any adhesive stuck to the front end faces of lensed fibers subsequently by facing (i.e., polishing) as in the case of ordinary optical fibers.
The present invention has been completed, in view of the above-mentioned problem, and therefore its object is to provide a lensed fiber array of such a structure that, when the substrate, the lensed fibers and the fixing member are to be fastened to one another with adhesive, the adhesive is not allowed from the outset to stick to the front end faces of the lensed fibers and a production method therefor.